As an FYI, as mentioned above the Paradigm Persona has beryllium on the tweeter and mid. I like that speaker a lot, but it needs warm gear. A very holographic sound and one I was seriously considering buying.
The speaker I mentioned above, the Yamaha NS5000, is the successor to the Yamaha NS1000 made in the 1970’s. It was the FIRST speaker with beryllium for the tweeter and midrange. About 40 years before Paradigm invented it.
The NS5000 has a material called Zylon that is supposedly lighter and faster than BE (or maybe the same). One difference is that Zylon is not poisonous like beryllium. Another thing is that Zylon can be made into a 12-inch woofer.
I am only mentioning all this because I would have easily discounted Yamaha as a top end speaker before I did more research and heard it. The tech in this NS5000 is very impressive. They have money and people for R+D.